What replacement part do I need for this

Old 12-03-17, 12:05 PM
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Join Date: Sep 2003
Location: Arlington, VA
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What replacement part do I need for this

The tube diameter is 4", the square opening that someone cut out is roughly 4.75" x 5.75".

The tube is coming from the bathroom below it, the bathroom fan blows the air up the tube and out the roof.

As you can see the tube is hanging by a thread so I'm looking for a fixture to secure the tube to and mount it to the opening so the bathroom's moist air isn't blowing into the attic.
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Old 12-03-17, 12:15 PM
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A 4" bath fan should be going to a 4" roof cap, not up to the Lomanco 750 "mushroom style" ventilation louvers that are for your attic ventilation. It's commonly done that way, but it's not exactly proper.

Here is a link to a roof cap exhaust louver.


You also need this collar along with it, sold separately.


The bath duct itself should be between the joists, kept low, buried in insulation. The bath fan roof cap should therefore also be low on the roof, not up high at the peak. When it's up high, hanging from a nail like it is in your picture, it just invites condensation to collect and run right back down the pipe, causing a leak in the bathroom during cold winter months.

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